The MCU used on the MC HCK already contains a 3.3V linear regulator
that allows operating from the 5V that are provided by USB. But not
every MC HCK will always be connected to USB – we have several power
supply options to cover these cases.

At the heart of the additional power supply options is a 3-way voltage
regulator footprint that can host an LDO, a step-down converter, and a
step-up converter.

For the upcoming shipment of the prototype kits, I will have to flash
the USB bootloader to all 250 bare microcontroller chips. Even though
we have a detailed description on how bootstrap the bootloader, I
rather have people be able to use their MC HCKs right away. This
article describes the flashing rig and software that I built for this
task.

I am happy to announce that we have a self-hosted toolchain: The MC
HCK can now act as SWD debug adapter for other MC HCKs, without
requiring any other external debug adapters or development boards.

The SWD interface is a debug interface, similar to JTAG; however, it
only requires two signal lines, and it is specific to ARM processors.
In the MC HCK toolchain, we use SWD to initially program the USB
bootloader, as well as to debug code. See below for a short example
session.

From the beginning, the MC HCK was conceived to be not only cheap to
produce and sell, but it was also conceived to be buildable at home,
at a low cost. In this post, we’ll show how to build a MC HCK at
home.

Given that we are still waiting for components for the prototype kit,
I used the opportunity to do another design iteration. The new design
features (hopefully) improved analog noise performance, and a
rearranged pin layout that allows to use the nRF24L01+ RF boards
directly on SPI.

We are happy to be able to announce the first prototype MC HCK dev
kits. These prototype kits are meant for early adopters, who would
like to evaluate and verify the electrical design of the MC HCK, and
those who want to contribute to the growing software library.